CN114184624A - Defect detection method and device for transparent medium thin layer - Google Patents
Defect detection method and device for transparent medium thin layer Download PDFInfo
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- CN114184624A CN114184624A CN202111351400.3A CN202111351400A CN114184624A CN 114184624 A CN114184624 A CN 114184624A CN 202111351400 A CN202111351400 A CN 202111351400A CN 114184624 A CN114184624 A CN 114184624A
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- transparent medium
- thin layer
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/84—Systems specially adapted for particular applications
- G01N21/88—Investigating the presence of flaws or contamination
- G01N21/95—Investigating the presence of flaws or contamination characterised by the material or shape of the object to be examined
- G01N21/958—Inspecting transparent materials or objects, e.g. windscreens
Abstract
The invention relates to the field of defect detection, in particular to a defect detection method and device for a transparent medium thin layer. The invention discloses a defect detection method and a device for a transparent medium thin layer, wherein the method comprises the following steps: s1, providing an incident light, making the incident light incident on the surface of the transparent medium thin layer to be measured at the total reflection angle or more; and S2, detecting whether the diffuse scattering light corresponding to the incident light exits from the transparent medium thin layer to be detected, if so, detecting that the transparent medium thin layer to be detected has defects. The invention can effectively and reliably detect the fine defects in the transparent medium thin layer, has convenient operation, high detection speed and high efficiency, saves a large amount of labor cost, and has simple equipment and low cost.
Description
Technical Field
The invention belongs to the field of defect detection, and particularly relates to a defect detection method and device for a transparent medium thin layer.
Background
In the process of manufacturing transparent optical media (such as flat lenses), various processing links are usually required, such as: processing a base die, depositing and coating, vacuum sputtering and coating and the like. Each link has processing defects, such as uneven sputtering of the target material, introduction of impurity particles by air drying, and the like, which are collectively referred to as defects. In order to avoid waste of processing resources, it is generally necessary to check whether the product processed by each process step is defective. The link can directly eliminate defective products, and avoid the waste of subsequent processing resources.
The existing defect detection technology mainly comprises CNC imager detection and manual visual observation. The CNC imager can carry out high-precision measurement, the repetition precision reaches +/-0.1 mu m, the 2000-thousand-pixel ultra-high-definition CMOS sensor can realize high-magnification measurement, but the observation area is limited, the position of a glass slide needs to be manually rotated, the detection speed is low, and the equipment cost is high. The artificial naked eye observation is that in a bright field, the lens is observed by using the automatic zooming function of human eyes and facing a projection light source at a certain angle, defects (blemishes) in a film layer can be observed, the equipment cost is low, but a large amount of manpower is required, the manpower cost is high, the lens is influenced by the visual fatigue of the human eyes, and false detection exists.
Disclosure of Invention
The invention aims to provide a defect detection method and a defect detection device for a transparent medium thin layer, which are used for solving the existing technical problems.
In order to achieve the purpose, the invention adopts the technical scheme that: a defect detection method for a transparent medium thin layer comprises the following steps:
s1, providing an incident light, making the incident light incident on the surface of the transparent medium thin layer to be measured at the total reflection angle or more;
and S2, detecting whether the diffuse scattering light corresponding to the incident light exits from the transparent medium thin layer to be detected, if so, detecting that the transparent medium thin layer to be detected has defects.
Further, in step S1, the incident light is collimated light.
Further, in step S1, the incident light is white light.
Further, in step S1, an LED light source or a laser driving light source is used to provide incident light.
Further, in step S2, a photodetector is used to detect whether the thin layer of transparent medium to be measured has diffusely scattered light corresponding to the incident light.
Further, the photodetector is a CCD photodetector or a CMOS photodetector.
Further, the photoelectric detector is arranged outside the surface of the transparent medium thin layer to be detected.
Further, in step S1, a light-transmitting coupling element is further provided, wherein a refractive index of the coupling element is greater than a refractive index of the transparent medium thin layer to be measured, the coupling element is attached to the surface of the transparent medium thin layer to be measured, and incident light is incident from the coupling element to the surface of the transparent medium thin layer to be measured at a total reflection angle or greater.
Further, the coupling piece is made of a transparent material.
The invention also provides a defect detection device of the transparent medium thin layer, which is used for realizing the defect detection method.
The invention has the beneficial technical effects that:
the invention can effectively and reliably detect the fine defects in the transparent medium thin layer, has convenient operation, high detection speed and high efficiency, saves a large amount of labor cost, and has simple equipment and low cost.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
FIG. 1 is a flow chart of a method of an embodiment of the present invention;
FIG. 2 is a schematic diagram of the evanescent wave defect detection principle of the present invention;
FIG. 3 is a schematic diagram of the evanescent wave defect detection principle of the present invention;
FIG. 4 is a schematic structural diagram of a defect detection apparatus according to an embodiment of the present invention;
FIG. 5 is a schematic structural diagram of a defect detection apparatus according to another embodiment of the present invention.
Detailed Description
To further illustrate the various embodiments, the invention provides the accompanying drawings. The accompanying drawings, which are incorporated in and constitute a part of this disclosure, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the embodiments. Those skilled in the art will appreciate still other possible embodiments and advantages of the present invention with reference to these figures. Elements in the figures are not drawn to scale and like reference numerals are generally used to indicate like elements.
The invention will now be further described with reference to the accompanying drawings and detailed description.
As shown in fig. 1, a method for detecting defects of a transparent dielectric thin layer includes the following steps:
s1, providing an incident light, making the incident light incident on the surface of the transparent medium thin layer to be measured at the total reflection angle or more.
And S2, detecting whether the diffuse scattering light corresponding to the incident light exits from the transparent medium thin layer to be detected, if so, detecting that the transparent medium thin layer to be detected has defects.
The detection principle is as follows:
as shown in fig. 2, when the incident light 100 is incident on the surface of a transparent medium 400 at the total reflection angle or the incident angle θ greater than the total reflection angle, total reflection occurs on the surface of the transparent medium 400, and at the same time, an evanescent wave 300 is generated at the surface of the transparent medium 400 and propagates along the surface, if there is no defect in the region of the transparent medium 400 corresponding to the propagation of the evanescent wave 300, then, except for the total reflection light 200, no diffusely scattered light exits from the transparent medium 400, forming a dark field background; if there is a defect 600 in the region of the transparent medium 400 corresponding to the propagation of the evanescent wave 300, the evanescent wave 300 is affected by the defect 600, and diffusely scattered (including forward scattering, backward scattering, etc.) light 500 exits, as shown in fig. 3, resulting in a brightness at the defect 600 that is much brighter than the dark-field background, which is easy to detect the defect, and therefore, if it is detected that the diffusely scattered light 500 corresponding to the incident light 100 exits from the transparent medium 400, it indicates that there is a defect in the region of the transparent medium 400 corresponding to the propagation of the evanescent wave 300.
Because the penetration depth of the evanescent wave is not more than 5 mu m, the invention is suitable for detecting whether the transparent medium thin layer with the thickness of not more than 5 mu m has defects. The transparent medium thin layer can be a transparent thin film with the thickness not more than 5 μm, and also can be a thick transparent thin film or a shallow surface layer with the depth not more than 5 μm of a thick transparent substrate. The invention is more suitable for a plane transparent medium thin layer.
In this embodiment, the transparent film 4 (as shown in fig. 4 and 5) with a thickness of not more than 5 μm on the substrate 5 is taken as an example for illustration, but not limited thereto. The substrate 5 may be a flat lens or the like.
Preferably, in this embodiment, the incident light 100 is collimated light, which is convenient for detection, reduces interference, improves detection accuracy, and has wider adaptability, but is not limited thereto, and in some embodiments, some incident lights with smaller divergence angles may also be used, as long as the incident lights are incident on the surface of the transparent medium thin layer to be detected at the total reflection angle or greater.
Preferably, in this embodiment, the incident light 100 is white light, and the detection effect is better, but not limited thereto, and in some embodiments, the incident light 100 may also be implemented by using light of other colors.
In this embodiment, the incident light 100 is preferably implemented by using a white LED light source 1, and as shown in fig. 4 and 5, white light emitted from the white LED light source 1 is focused, expanded and shaped by a lens unit 2 into a line light source as the incident light 100. The incident light 100 is realized by using the white LED light source 1, which is easy to implement and low in cost, but not limited thereto.
In the present embodiment, the lens unit 2 includes two cylindrical lenses 21 and a diaphragm 22, but is not limited thereto, and in some embodiments, other existing lens units may be used.
Of course, in some embodiments, the incident light 100 may be provided by other broad spectrum light sources such as laser-driven light sources.
Specifically, in step S2, the photodetector 3 is used to detect whether the diffuse light corresponding to the incident light 100 exits from the transparent film 4 to be detected, so as to facilitate automatic detection, improve detection efficiency and reliability, and reduce labor cost.
In this embodiment, the photodetector 3 is preferably a CCD photodetector or a CMOS photodetector, which is easy to implement and has a good detection effect. The field angle of the photodetector 3 covers the region to be detected of the transparent film 4 to be detected.
The photodetector 3 is disposed on the outer side of the surface of the transparent film 4 to be detected, and can be on the same side as the incident light 100 (see fig. 5) to detect forward scattering, or on the other side opposite to the incident light (see fig. 4) to detect backward scattering, so that the operation is convenient and flexible.
Further, as shown in fig. 5, in step S1, a light-transmitting coupling element 7 is further provided, a refractive index of the coupling element 7 is greater than a refractive index of the transparent film 4 to be measured, the coupling element 7 is closely attached to the surface of the transparent film 4 to be measured, and the incident light 100 is incident from the coupling element 7 to the surface of the transparent film 4 to be measured at a total reflection angle or greater.
Preferably, the coupling element 7 is made of a transparent material, and is suitable for incident light of various colors, and has good applicability and good detection effect, but not limited thereto, and in some embodiments, the coupling element 7 may also be made of a material that is transparent but opaque.
Preferably, the coupling piece 7 is made of a flexible material, so that the coupling piece can be tightly attached to the surface of the transparent film 4 to be detected, interference is reduced, and detection accuracy is improved. The coupling member 7 may be made of a transparent material such as chromium oxide.
The coupling piece 7 can be made into a strip-shaped structure and periodically and transversely moves along with the region to be detected during detection so as to meet the detection requirement of each region on the large-size transparent film 4 to be detected. In addition, the coupling element 7 may also be processed into a flexible planar standard component with the same size as the transparent film 4 to be detected, and attached to the transparent film 4 to be detected, and then the incident light 100 is moved to realize the detection of each area on the large-sized transparent film 4 to be detected.
Of course, in the case that the material of the substrate 5 is transparent and the refractive index is greater than the refractive index of the transparent film 4 to be measured, the coupling element 7 may not be needed, and the incident light 100 directly enters from the substrate 5 and enters at the total reflection angle or greater to the surface of the transparent film 4 to be measured, as shown in fig. 4, and the detection is simpler and more convenient. Of course, this also applies to the case where the substrate 5 is a light-transmitting but opaque material.
Of course, in some embodiments, the incident angle of the incident light 100 can be changed by disposing the reflector 6, which is more convenient for use.
Preferably, the transparent film 4 to be detected is placed in a dark field environment for detection, so that the interference of ambient light can be eliminated, the detection accuracy is improved, the requirement on the performance of the photoelectric detector 3 is reduced, and the cost is reduced.
When a plurality of layers of transparent films are to be detected, layer-by-layer detection can be carried out, namely, the detection is carried out once every layer of transparent film is plated, and the next layer of transparent film is plated after the detection is qualified.
Array extension can be achieved by increasing the number of systems, batch detection can be achieved, and complete mechanical operation can be achieved for lenses in production and processing.
The invention also provides a defect detection device of the transparent medium thin layer, which is used for realizing the defect detection method.
In this embodiment, the specific structure of the defect detecting apparatus for a transparent dielectric thin layer is shown in fig. 4 or 5, and please refer to the above description for further details, which will not be described in detail. But not limited thereto, and in some embodiments, other structures may be adopted.
The invention can effectively and reliably detect the fine defects in the transparent medium thin layer, has convenient operation, high detection speed and high efficiency, saves a large amount of labor cost, and has simple equipment and low cost.
While the invention has been particularly shown and described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (10)
1. A defect detection method for a transparent medium thin layer is characterized by comprising the following steps:
s1, providing an incident light, making the incident light incident on the surface of the transparent medium thin layer to be measured at the total reflection angle or more;
and S2, detecting whether the diffuse scattering light corresponding to the incident light exits from the transparent medium thin layer to be detected, if so, detecting that the transparent medium thin layer to be detected has defects.
2. The method for detecting defects in a thin transparent dielectric layer as claimed in claim 1, wherein: in step S1, the incident light is collimated light.
3. The method for detecting defects in a thin transparent dielectric layer as claimed in claim 2, wherein: in step S1, the incident light is white light.
4. A method for defect detection of a thin layer of transparent medium as claimed in claim 3, wherein: in step S1, an LED light source or a laser driving light source is used to provide incident light.
5. The method for detecting defects in a thin transparent dielectric layer as claimed in claim 1, wherein: in step S2, a photodetector is used to detect whether the thin layer of transparent medium to be measured has diffusely scattered light corresponding to the incident light.
6. The method of claim 5, wherein the step of detecting the defects comprises: the photoelectric detector is a CCD photoelectric detector or a CMOS photoelectric detector.
7. The method of claim 5, wherein the step of detecting the defects comprises: and arranging the photoelectric detector outside the surface of the transparent medium thin layer to be detected.
8. The method for detecting defects in a thin transparent dielectric layer as claimed in claim 1, wherein: in step S1, a light-transmitting coupling element is further provided, the refractive index of the coupling element is greater than the refractive index of the thin transparent medium layer to be measured, the coupling element is attached to the surface of the thin transparent medium layer to be measured, and the incident light is incident from the coupling element to the surface of the thin transparent medium layer to be measured at a total reflection angle or greater.
9. The method of claim 8, wherein the step of detecting the defects in the transparent dielectric thin layer comprises: the coupling piece is made of transparent materials.
10. A defect detection device of a transparent medium thin layer is characterized in that: for implementing the defect detection method of any one of claims 1-9.
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| CN202111351400.3A CN114184624A (en) | 2021-11-16 | 2021-11-16 | Defect detection method and device for transparent medium thin layer |
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| CN202111351400.3A CN114184624A (en) | 2021-11-16 | 2021-11-16 | Defect detection method and device for transparent medium thin layer |
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